Three pivotal things
happened during this time. Each occurred during a period of global
climatic upheaval and they all happened in Africa. First hominines
descended from the trees to walk on two feet. Then tool making
emerged, made possible by a larger brain and two hands. Finally,
people belonging to the Homo genus evolved. They had bodies
with human proportions and complex bilateral brains two-thirds the size
of modern humans. Sexual competition was reduced by greater
equality between males and females and a more influential role for
fathers during the long years of human childhood.

.

Walking on Two Feet

7
Million Years Ago

The first
primates who walked on two feet, lived in Africa. Why this
two-foot fashion caught on is a source of some scientific debate as the
evolutionary advantage 7 million years ago is not so clear. As
many as 20 or 30 bi-pedal species may have appeared and disappeared
throughout Africa between 7 and 3 million years ago. Among them
are our ancestors.

Archaeologists have found
what we would probably call a tool factory in Olduvai Gorge, Tanzania,
Africa.

Between 2.9 and 2.5 million years old it is the oldest
evidence of the systematic manufacture of stone tools. Scientists
believe the tools were first made by Homo habilis, an intelligent
primate but not really of the Homo genus.

Supernova explosions in
our solar system's neighbourhood five and two million years ago may have
shaken Earth to its core. They may have created the Local Bubble,
an almost empty space that surrounds us and makes it possible for us to
see the stars. Nobody knows for sure if the explosion caused the
north and south magnetic reversals that occurred at this time... or if
these events explain a series of sudden extinctions that left room for
human evolution to continue.

Homo ergaster
(workman) and Homo erectus his later relative, clearly belong to
the Homo genus. Their brains were two thirds the size of
ours. Their tools and weapons were more sophisticated than
earlier implements. They constructed rudimentary dwellings and
their social relations were more cooperative. They were the first
hominins to leave Africa moving through Eurasia and China, and by
800,000 years ago hominins had arrived in Europe.

Some scientists
believe that Homo erectus is the founding father of all
later humans while other scientists believe that the lines of erectus
and ergaster diverged.